Slide-valve for steam-engines



UNITED STATES PATENT OFFICE.

THOMAS WINANS, OF BALTIMORE, MARYLAND.

SLIDE-VALVE FOR STEAM-ENGINES.

Specification of Letters Patent No. 17,712, dated Tune 30, 1857.

To all whom il may concern.'

Be it known that l, THOMAS WiNANs, of the city of Baltimore, in the State of Maryland, have invented a new and useful lmrovement in the Slide-Valves of Steam- 4ngines, and that the following is a full and exact description of my said improvement.

My improvement is applicable to those cases where a secondary valve, moving immediately upon a principal slide valve, is used for the purpose of cutting off the supply of steam at given portions of the stroke of the iston.

Through the principal or lower valve, as ordinarily constructed, there are always two distinct channels at least for the steam, one communicating with the port at one end and the other with the port at the other end of the cylinder, the opening communicating with the exhaust being between the two. The secondary valve is used to control the time that these two channels through the main valve remain open for the admission of the steam.

The accompanying sketch Figure l which represents Myers expansion valve, described in Clarks Railway Machinery," page 28, A being the main and B being the secondary valve, illustrates my meaning.

The object of my improvement is to diminish the wire-drawing of steam, which occurs when a cut-O-valve is closing, without increasing the dimensions of the steam chest and slide valve beyond what is now used or to an inconvenient or objectionable size. l

accomplish this desideratum by connecting the aforesaid openings through either end of the main valve by a channel or o ening represented by dotted lines a, a, in flyers valve Fig. 1, and by l2 in the drawing Fig. 3, thereby allowing the steam to pass through both openings alternately into either end of the cylinder-the valve being so constructed as to close and open each opening at the same instant.

lt will be perceived, by the accompanying diagrams, Figs. 2 and 3 that while the motion of the two valves remains the same, the one made by the valve with channel, Fig. 3, between the end openings retains the area into the cylinder from being diminished, until the out off valve has arrived-much nearer the iinal cut off, hence the closing the induction opening into the cylinder takes place in much less or about half the time than would be the case if no channel connected the openings through either end of the main valve as before described, resulting in a material difference in the wire drawing of the steam.

What I claim as new and wish to secure by Letters Patent is- The connecting of the passages through the ends of the main valve, herein denominated the Myers valve, by the channel or opening herein described.

THOS. WINANS.

Witnesses:

OsMUN LATROBE, T. E. THOMAS, Jr. 

